Injection device

ABSTRACT

An injection device comprising a housing in which can be mounted a syringe comprising
         a barrel for holding a volume of medicament,   a needle at one end of the barrel and   a plunger axially-moveable in the barrel to a forwardmost position, the injection device further comprising a syringe support means for supporting the barrel at an axial location at or forward of the forwardmost position of the plunger and having a reaction surface for the syringe, whereby in use said reaction surface provides an axial compressive force on said barrel when a forward axial force is applied to the plunger.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. §119 to UnitedKingdom Patent Application Nos. GB0601309.8 filed Jan. 23, 2006,GB0602411.1 filed Feb. 7, 2006, and GB filed Mar. 21, 2006. The entiredisclosures of the above-referenced patent applications are incorporatedherein by reference in their entirety.

FIELD

This invention relates to the field of injection devices for theadministration of liquid medication, for example, interferon.

BACKGROUND

One typical known device is described in WO00/09186 (Medi-JectCorporation) for “Needle assisted jet injector” and this document givesa useful summary of other prior art devices.

The device of WO 00/09186 includes a needle which is, in one embodiment,retractably located within an injector nozzle assembly. Upon activationof a force-generating source, a portion of the needle extends past thenozzle assembly and penetrates the outer layer of skin to delivermedicament via jet injection to a deeper region. After activation, theneedle retracts back into the nozzle assembly. The retractable needle ishoused within the nozzle and is pushed forward so that it emerges inorder to deliver an injection by the liquid medicament itself, when themedicament is itself pushed forward by the plunger.

Another injection device is described in our co-pending internationalpatent application, published under number WO 2005/070481. Some of thereference numerals in the present application correspond with theequivalent components in the device described in WO 2005/070481. Thisdevice requires that the needle is moved axially so that it can appearbeyond the end of the nozzle for the duration of the injection, afterwhich the needle retracts automatically, so that it is never in sight ofthe user. The device also requires that the plunger is moved axially sothat medicament is ejected. The overall complexity of the injectiondevice is significantly reduced by both of these requirements beingeffected by one component, namely an inner housing and the device hasthe significant advantage that it can be built around a conventional orstandard syringe presentation.

The injection device of WO 2005/070481 is designed to be used inconjunction with a standard drug presentation e.g. a syringe comprisinga needle, barrel preloaded with medicament and a plunger. There is asignificant commercial advantage in being able to use a standardsyringe, which will have been subjected to numerous clinical trials,drug stability studies and regulatory approval. Any modification to thestandard syringe may require further trials and approval, adding delayand expense. The present invention is relevant to any injection devicefor use in conjunction with a syringe (whether preloaded or not andwhether single-use or reusable), not only the device described in WO2005/070481.

The barrel of a syringe is usually glass, since glass has the mostfavourable storage properties for many drugs. However, glass isnotoriously fragile and there is a risk of damage or breakage of thesyringe during injection if the forces to which the syringe is subjectedby the injection device are not properly controlled. This isparticularly so where the liquid medicament is relatively viscous,requiring greater force to expel it from the syringe via the needle.Barrels made of materials other than glass, for example polyethylene orcyclic olefin polymers are less brittle when subjected to normal forcesduring injection, but still would benefit from the invention describedbelow.

In the known device described in our co-pending patent application no WO2005/070481 and illustrated in FIGS. 1-3 of the present application, thesyringe is supported within the injection device by a barrel or syringeholder 9. The syringe holder 9 comprises an elongate housing whichclosely surrounds the glass barrel of the syringe. The annular flange 90at the rear of the syringe barrel rests on a barrel seat 91 at the rearof the syringe holder 9. The annular flange 90 at the rear of thesyringe barrel is often referred to as a “finger flange” because, duringa conventional (manual) injection using a syringe, the user's index andmiddle fingers rest naturally in front of the “finger flange” in orderto provide the necessary resistance to allow depression of the plungerby the thumb to deliver the medicament.

The barrel seat, for example in the form of an annular flange,preferably prevents forward axial movement of the syringe with respectto the syringe holder so that, in use, the syringe barrel and thesyringe holder move axially together as one unit.

In use, as described in WO 2005/070481, there are three stages ofdelivering an injection. Before delivering an injection (referring toFIG. 1 of the present application), the end cap 15 is pulled off, takingthe rigid needle cover 17 (if present) and rubber needle sheath 16 withit. In the first stage of delivering an injection, as shown in FIG. 2 ofthe present application, the tags 7B at the forward end of the innerhousing 7 are in contact with the syringe barrel 90, which is pushedaxially forward (taking the syringe holder 9 with it), so that theneedle 10, which is fixed to the front end of the barrel, moves in thedirection indicated by the arrow so that eventually it protrudes beyondthe nozzle 11 at the front of the device. Forward travel of the barreland syringe holder is limited when a surface 9A of the syringe holderreaches an endstop 11A inside the nozzle or front housing 11.

Referring now to FIG. 3 , the second stage of the injection is thedelivery of the medicament wherein the tags 7A at the rear of the innerhousing 7 depress the plunger 8 into the barrel of the syringe. Duringthis stage, the barrel of the syringe is held axially stationary, byabutment of the annular “finger” flange 90 against the barrel seat 91,which results in the barrel being placed in tension as the plungerpushes the non-compressible liquid medicament towards the forward end ofthe barrel. This tension is undesirable in a glass barrel, which maybecome damaged or broken, especially if the medicament comprises aparticularly viscous liquid which requires greater force to expel itfrom the syringe via the needle. Viscous medicaments are desirable incertain applications, where the use of a sustained-release viscousmedicament reduces the frequency that an injection is required.

It is desirable to minimise the diameter of the needle so far as ispossible, because the smaller the diameter of the needle, the lesspainful is the resulting injection. However, for a given length ofneedle, the smaller the needle diameter, the greater the force requiredto eject the medicament from the syringe.

It is also desirable to minimise the duration of the injection, i.e. tomaximise the speed at which the medicament is delivered from thesyringe. Particularly when the needle diameter is small, minimising theduration of the injection also means an increase in the force used toeject the medicament from the syringe.

An increase in the forces on the syringe consequently increases thelikelihood of the syringe breaking during the injection. The risk of thesyringe breaking during injection is significant, and is not onlyinconvenient and costly but is also potentially dangerous. If breakageoccurs, it is possible that glass fragments and/or the needle may becomedetached and exit the front of the device causing injury. Furthermore,there is the risk that the remaining medicament will leak or be ejectedfrom the device in an uncontrolled manner, potentially delivering thewrong dose into the patient, or causing injury e.g. if the medicamentcontacts the patient's skin or eyes. These problems are amplified whenthe medicament is viscous as a more powerful energy source is needed insuch applications so that the forces involved are greater. It is knownthat a typical breakage of the syringe during injection would occur atthe finger flange, whereby the finger flange 90 on the syringe barrelbreaks as a result of its abutment against the barrel seat 91. It istherefore highly desirable to minimise the likelihood of breakage of thesyringe.

In the third stage of the injection (not illustrated in the presentapplication but shown in WO 2005/070481), once the medicament has beendelivered and the inner housing 7 is no longer in contact with thebarrel or plunger of the syringe, the secondary spring 12 pushes thesyringe holder (and hence the syringe contained therein) axiallyrearwardly so as to retract the syringe back into the housing so thatthe used needle is concealed from view.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, there is providedan injection device comprising a housing in which can be mounted asyringe comprising

-   -   a barrel for holding a volume of medicament,    -   a needle at one end of the barrel and    -   a plunger axially-moveable in the barrel to a forwardmost        position,        the injection device further comprising a syringe support means        for supporting the barrel at an axial location at or forward of        the forwardmost position of the plunger and having a reaction        surface for the syringe, whereby in use said reaction surface        provides an axial compressive force on said barrel when a        forward axial force is applied to the plunger.

According to a second aspect of the invention there is provided a methodof assembling an injection device comprising the steps of:

-   -   providing a first part-assembly comprising a front housing and a        closely fitting end cap;    -   providing a second part-assembly comprising a rear part of the        injection device;    -   providing a syringe comprising a barrel for holding a volume of        medicament, a needle at one end of the barrel and a plunger        axially-moveable in the barrel;    -   providing a syringe support means;    -   inserting the syringe axially into the rear end of the syringe        support means until said syringe support means supports the        syringe at a predetermined axial location;    -   inserting the front end of said syringe and syringe support        means into said first part-assembly;    -   assembling said first part-assembly and second part-assembly        together.

According to a third aspect of the invention there is provided a methodof assembling an injection device comprising the steps of:

-   -   providing a first part-assembly comprising a syringe support        means, a front housing and a closely fitting endcap;    -   providing a second part-assembly comprising a rear part of the        injection device;    -   providing a syringe comprising a barrel for holding a volume of        medicament, a needle at one end of the barrel and a plunger        axially-moveable in the barrel;    -   inserting the syringe axially into the rear end of the first        part-assembly until said syringe support means supports the        syringe at a predetermined axial location;    -   assembling said first part-assembly and second part-assembly        together.

Further features of the invention are defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the present invention will now be moreparticularly described, by way of example only, with reference to theaccompanying drawings in which:

FIG. 1 (PRIOR ART) is a perspective view of a known injection device;

FIG. 2 (PRIOR ART) is a plan view, partly in section of the FIG. 1device, with the cap and needle cover removed, ready for actuation;

FIG. 3 (PRIOR ART) is a plan view, partly in section of the FIG. 1device, with the needle exposed, ready for the plunger to be depressedin order to deliver the medicament;

FIG. 4 is a perspective view of an injection device embodying one aspectof the present invention;

FIG. 5 is a plan view, partly in section of the FIG. 4 device, with thecap and needle cover removed, ready for actuation;

FIG. 6 is a plan view, partly in section of the FIG. 4 device, with theneedle exposed, ready for the plunger to be depressed in order todeliver the medicament;

FIG. 7 is a perspective view of the syringe holder;

FIG. 8 is a cross-sectional view of the syringe holder of FIG. 7 ;

FIG. 9 is a cross-section view of the syringe holder of FIG. 7 , showinga syringe in place;

FIG. 10 is a cross-section view of the syringe holder of FIG. 7 ,showing a syringe and rigid needle cover in place;

FIG. 11 shows detail, drawn to a larger scale, of the interface betweenthe front of the glass syringe barrel and the syringe holder illustratedin FIG. 10 ;

FIG. 12 , drawn to a larger scale, is a cross-sectional view of themodified front housing;

FIG. 13 , drawn to a larger scale, is a perspective cross-sectional viewof the front housing;

FIG. 14 is a cross-sectional view of the front housing, cap and syringeholder assembled together;

FIG. 15 is a perspective view of the front housing, cap and syringeholder assembled together;

FIG. 16 is a cross-sectional view of the front housing, cap, syringeholder and syringe assembled together;

FIG. 17 is a cross-sectional view of an alternative embodiment of thesyringe holder;

FIG. 18 is a part-assembly view showing the syringe holder of FIG. 17together with its spring retainer, a syringe therein and the end cap andfront housing;

FIG. 19 shows the part-assembly of FIG. 18 with the rigid needle coverremoved;

FIG. 20 is a perspective view of the syringe holder of FIG. 17 togetherwith its spring retainer;

FIG. 21 is a perspective view of a syringe holder, end cap and fronthousing, showing an alternative means of retaining the gripping meansagainst the syringe barrel;

FIG. 22 is a perspective view of the syringe holder of WO 2005/070481,modified in accordance with an alternative embodiment of the invention;and

FIG. 23 is a perspective view of another embodiment of the syringeholder together with a needle cover.

DETAILED DESCRIPTION

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of the words, for example“comprising” and “comprises”, means “including but not limited to”, andis not intended to (and does not) exclude other components, integers orsteps.

Throughout the description and, claims of this specification, thesingular encompasses the plural unless the context otherwise requires.In particular, where the indefinite article is used, the specificationis to be understood as contemplating plurality as well as singularity,unless the context requires otherwise.

Throughout the following description, reference to a “forward” directionmeans the direction which is towards the patient when the injectiondevice is in use. The “forward” end of the injection device is the endnearest the patient's skin when the device is in use. Similarly,reference to a “rearward” direction means the direction which is awayfrom the patient and the “rearward” end of the device is the endfurthest from the patient's skin when the injection device is in use.

Features, integers, characteristics or groups described in conjunctionwith a particular aspect, embodiment or example of the invention are tobe understood to be applicable to any other aspect, embodiment orexample described herein unless incompatible therewith.

As described above, a disadvantage of the known prior art is that thebarrel of the syringe is placed in tension as the plunger pushes thenon-compressible liquid medicament towards the forward end of the barrelfor delivery. This tension is undesirable in a glass barrel, which maybecome damaged or broken, especially if the medicament comprises aparticularly viscous liquid which requires greater force to expel itfrom the syringe. There is a possibility that the glass syringe mightbreak in the region of its finger flanges, as a result of the forces towhich it is subjected during delivery of an injection. One way tomitigate this problem is to reduce the effect of those forces in theregion of the finger flanges. For example, the syringe holder of WO2005/070481 can be modified as illustrated in FIG. 22 . The syringeholder 9 has a helical slit 92 which, in use, provides resilience to theregion of the barrel seat 91 on which is located the finger flange ofthe syringe (not illustrated). The resilient flexing absorbs shock andreduces the risk of breakage of the syringe in the region of the fingerflanges.

Other means for reducing the effect of forces in the region of thefinger flanges can be envisaged, for example, providing a cushion in theform of an O-ring or moulding a relatively soft or elastomeric materialinto a harder substrate in the region of the barrel seat 91.

It is known that a typical breakage of the syringe during injectionwould occur at the finger flange, whereby the finger flange 90 on thesyringe barrel breaks as a result of its abutment against the barrelseat 91. However, the applicant has recognised that it is also possiblethat the syringe could break at the forward end of the barrel. This ispotentially more serious as larger straight glass fragments may beejected from the front of the device, as well as the unsecured needle,and any remaining medicament will leak out in an uncontrolled manner.

The risk of breakage or damage to the glass syringe may be reduced byensuring that the barrel is held in compression during delivery of themedicament (stage two of the injection process described in WO2005/070481), rather than being in tension. This can be achieved bysupporting the forward end of the barrel and having a reaction surfaceat which an axial compressive force can be applied to the barrel when aforward axial force is applied to the plunger during delivery of themedicament.

In the injection device of the present invention, the conventionalsyringe holder 9 is replaced with a more complex syringe holder which iscapable of supporting the syringe at the front end of its barrel insteadof at its rear flange 90 during delivery of the medicament. In theembodiment described below, the syringe holder supports the syringe atthe front shoulder of its barrel and provides a reaction surface therefor the front shoulder of the barrel. By “front shoulder” is meant theregion at which the largest diameter of the barrel reduces to a smallerdiameter at the nozzle. The front shoulder 92 is indicated in FIG. 9 .Alternatively, the syringe could be supported and the reaction surfaceprovided at the front end of the syringe barrel, or at the narrowed“cone” where the needle is attached thereto and these embodiments aredescribed in more detail below. The syringe can, in fact, be supportedat any place on the barrel which, in use, is forward of the forwardmostposition of the fully-depressed syringe plunger and where a reactionsurface for the syringe can be provided (so that the barrel is held incompression throughout the delivery of the medicament).

However, the desired supporting or holding of the barrel by the syringeholder at its front end presents an assembly difficulty for a productwhere it is desired to keep manufacturing and assembly costs to aminimum. In the prior art device, the syringe can simply be dropped intothe rear end of the syringe holder until its flange 90 rests on thebarrel seat 91. This determines the axial position of the syringe withrespect to the syringe holder. In practice, the prior art syringe holderis supplied ready-assembled with the front part of the device, so thatthe pre-filled syringe can simply be dropped into the syringe holder andthen the front part of the device (including the syringe) can beattached to the ready-assembled rear part of the device in a simpletwo-stage assembly operation.

In the present invention, it is not possible to use the finger flange 90and barrel seat to determine the axial position of the syringe withrespect to the syringe holder. This is because the syringe holder needsto actively support the syringe at its front end (preferably at thefront shoulder 92 of the glass barrel). In the preferred embodimentthere are inwardly-directed gripping means to retain the front shoulderof the glass barrel at a specific axial location with respect to thesyringe holder. The standard syringe is usually supplied with a rigidneedle cover 17 which has a diameter almost the same as the largestdiameter of the glass barrel (see FIG. 10 ). If the syringe is insertedinto the syringe holder needle-first (or rather needle-cover first), anyinwardly-directed gripping means would foul on the rigid needle cover asit attempts to pass. There is also the risk of the needle being damagedduring assembly, for example if it is pushed into any inwardly-directedgripping means. Such damage to the needle is highly undesirable, inparticular because it often cannot be readily detected (if the needle isconcealed within a rigid needle cover and/or a rubber needle sheath. Thedamage to the needle only becomes apparent during delivery of themedicament.

This problem is solved by the use of a syringe holder 100 as illustratedin FIGS. 7 and 8 . The syringe holder 100 comprises an elongate rearportion 102 in which there are viewing windows 103 so that themedicament chamber in the barrel of a syringe held therein would bevisible. There is a barrel seat 101 (equivalent to barrel seat 91 in theprior art device) at the rear end of the rear portion 102, but inpractice this is not intended to abut the flange 90 of the syringebarrel (unlike in the prior art device).

The syringe holder also has an intermediate portion 105 of comparablediameter to the rear portion, and a front portion 106 of narrowerdiameter. The intermediate portion 105 is provided with a discontinuousannular flange 104. Together, the intermediate and front portions 105,106 include radially-spaced slots 107 which define a plurality ofradially flexible fingers 108. In the illustrated embodiment, there arethree flexible fingers 108, but four or some other number of fingers maybe provided. FIG. 23 shows an embodiment in which four flexible fingers108 are provided on the syringe holder 100. The four fingers necessarilyeach are thinner than those in the three-finger embodiment. A typicalneedle cover 17 is shown in FIG. 23 (illustrated without the rest of thesyringe for simplicity). The needle cover has a slot 17A therein. If thesyringe holder 100 is appropriately aligned with the needle cover of asyringe held therein, there is a possibility that one of the relativelythin flexible fingers 108 may undesirably snag or drop into slot 17A,possibly causing damage to the underlying needle that would not becomeapparent until an injection is delivered. This disadvantage can beovercome by ensuring that each of the flexible fingers 108 is preferablywider than the needle cover slot 17A, as illustrated by the three-fingerembodiment of FIG. 7 .

As shown in FIG. 8 , gripping means 109 preferably in the form of adiscontinuous annular inwardly-directed protrusion, are provided on theinterior of the flexible fingers 108 in the intermediate section 105.Referring to FIG. 9 , when a syringe is located within the syringeholder 100, the gripping means 109 abuts the front shoulder 92 of thebarrel in order to define the axial position of the barrel with respectto the syringe holder.

The term “gripping means” is not limited to means which gripradially-inwardly onto the barrel, although in some embodiments they maydo so. More important is the fact that the gripping means 109 (orequivalent) supports the syringe in a desired axial location andprovides a reaction surface for the syringe so that the barrel will beheld in compression during delivery of the medicament.

As can be seen from FIGS. 10 and 11 , the rigid needle cover 17 has agreater diameter than the diameter normally available at the grippingmeans 109. In other words, the internal diameter between the grippingmeans 109 is smaller than the exterior diameter of the needle cover 17.However, as will be explained in more detail below, when the syringe isinserted into the syringe holder, as the rigid needle cover 17 passesthe gripping means 109, the flexible fingers 108 flex radially-outwardlyto create sufficient diameter for the needle cover to pass theinwardly-protruding gripping means, without exerting excessive force onthe needle therein, thus minimising the risk of damage to the needle.Once the needle cover has passed, the flexible fingers 108 spring backinto their normal position (having smaller internal diameter than theexterior diameter of the needle cover) and the gripping means 109 locateat the front shoulder 92 of the barrel. In this position, the grippingmeans 109 are axially located between the needle cover and the frontshoulder of the barrel.

The front portion 106 of the syringe support 100 is provided with aplurality (preferably two) equispaced tags 110, whose purpose will bedescribed later below.

The most straightforward way to assemble the syringe and injectiondevice is in a three stage procedure, namely:

-   -   1. inserting the syringe into the syringe holder, until the        gripping means 109 locate at the front shoulder 92 of the        barrel;    -   2. inserting the syringe and syringe holder into the front part        of the injection device;    -   3. assembling the front part to the rear part of the injection        device.

Compared with the two-stage assembly procedure of the prior art device,the extra assembly stage is disadvantageous but initially seemsnecessary as it is not obvious how stages 1 and 2 could be readilycombined so that the syringe holder can be supplied ready-assembled withthe front part of the device. This is because, once assembled into thefront part of, the device, the flexible fingers 108 would be preventedfrom flexing radially outwardly by their necessarily close abutment withthe front housing, thus preventing insertion of the syringe and rigidneedle cover.

Therefore, in a further embodiment of the invention, a modified fronthousing for the injection device is provided which enables a two-stageassembly procedure to be used.

The modified front housing 200 (analogous to nozzle 11 in the prior art)is illustrated in FIG. 12 . The front housing 200 has a bore 201, ofsufficient diameter to allow passage therethrough of the needle 10,needle cover 17 and the front and intermediate portions 105, 106 of thesyringe holder (but not the flange 104).

The interior surface of the bore 201 is provided with two (or more)equispaced longitudinal slots 202, each having a rear section 203 with atapered surface providing a varying depth and a forward section 204 ofsubstantially constant depth. The boundary between the forward and rearsections of each slot 202 is defined by a step 205.

The slots 202 are positioned so that they can be aligned with the tags110 at the front portion of the syringe holder.

The slots 202 enable the syringe holder 100 to be assembled into thefront housing 200 at a specific axial position (relative to the fronthousing) so that the flexible fingers 108 stand clear of the fronthousing instead of being surrounded therein.

The slots 202 also provide radial location for the syringe holder 100 asit is inserted therein.

FIG. 14 shows a modified end cap 300 (analogous to end cap 15 in theprior art) designed for use with the modified front housing 200 and howthe syringe holder 100 is inserted into the front housing 200. The fronthousing 200 is inserted into the end cap 300 so that its leading surface206 abuts the interior of the end cap, so that no further forwardmovement of the front housing within the end cap is possible.

The close abutment of the end cap 300, front housing 200 and syringeholder 100 means that, if present, the rigid needle cover 17 is retainedsecurely in position such that the risk of the needle cover accidentallybecoming loose or detached is minimised, thereby minimizing possibleloss of integrity of the seal between the rubber needle sheath and theneedle, which would otherwise compromise the sterility of the medicamentcontained within the syringe.

The end cap has an upstanding annulus 301 which protrudes into and is aclose fit in the bore 201 of the front housing 200. The upstandingannulus 301 has two equispaced protrusions on the exterior surfacethereof which locate in longitudinal slots 202 when the end cap andfront housing are assembled together. Once assembled together, theupstanding annulus of the end cap and the step 205 together define aspace 302 into which tags 110 on the syringe holder 100 can locate.

In order to insert the syringe holder 100 into the front housing 200,the tags 110 are aligned with and pushed into the slots 202 until thetags 110 “click” over the step 205 and locate in the space 302. This isthe position illustrated in FIGS. 14 and 15 . Now the syringe holder 100is suitably axially located such that the gripping means 109 andflexible fingers 108 are not constrained within the front housing 200and end cap 300.

The front housing, end cap and syringe holder are supplied in thisready-assembled condition, together with the ready-assembled rear partof the injection device, for final assembly with a pre-filled syringe.

It is therefore a straightforward two-stage procedure to finallyassemble the syringe into the device, namely:

-   -   1. inserting the syringe into the ready-assembled front housing,        end cap and syringe holder until the gripping means 109 locate        at the front shoulder 92 of the barrel (as shown in FIG. 16 );    -   2. assembling the front part to the ready-assembled rear part of        the injection device (not illustrated).

FIGS. 4-6 show the fully assembled injection device including syringeholder 100. With reference to FIG. 5 , it can be seen that (unlike inthe prior art device) the flange 90 of the barrel does not contact thebarrel seat 101 of the syringe holder 100, there being a gap Gtherebetween. This is a result of the relative axial positions of thesyringe holder and syringe being determined at the front end, bygripping means 109 and front shoulder 92 and means that undesirabletension is not applied to the glass barrel during delivery of themedicament.

An alternative embodiment of the syringe holder is illustrated in FIGS.17-20 . Where possible, the same reference numerals as were used inrelation to FIGS. 8-9 are used to identify like components of thealternative embodiment. Note that FIGS. 17-20 show the front end of thedevice at the left side of the Figures, whereas FIGS. 8-9 show the frontend of the device at the right side of the Figures.

In the FIG. 17 embodiment of the syringe holder 100′, theradially-flexible fingers 108′ have their free ends extending in theforward direction (compare with the radially-flexible fingers 108 inFIG. 8 which have their free ends extending in the rearward direction).The gripping means comprise inwardly-directed enlarged heads 109′ at theend of the flexible fingers 108. As is best seen in FIG. 19 , theenlarged heads 109′ are capable of gripping the cone 93 at the front ofthe syringe barrel. The cone 93 is the region where the needle 10 isattached to the syringe barrel.

As shown in FIG. 18 , when a syringe is assembled with the syringeholder 100′, the rigid needle cover 17 (which is of comparable diameterto the syringe barrel) causes the flexible fingers 108′ to flexradially-outwardly so that the enlarged heads 109′ rest on the exteriorof the needle cover 17.

When the end cap 300 and rigid needle cover 17 are removed axially inthe direction of the arrow in FIG. 18 , the enlarged heads 109′ shouldmove radially-inwardly into contact with the cone 93 of the syringe soas to grip the front end of the barrel to provide the compressive forceduring injection. However, if the flexible fingers 108′ are made fromplastic and if the device is stored in the FIG. 18 configuration formany months before use (both of which are likely), it is possible thatthe fingers 108′ will no longer automatically flex properly inwardlyupon removal of the needle cover 17.

Therefore, a spring retainer 111 is provided. The spring retainer 111 ismade from steel, other metal or other material which does notsignificantly lose its resilience over time. The spring retainer haselongate fingers which cooperate with the flexible fingers 108′ so as tourge them radially-inwardly. Once the needle cover 17 has been removed,the spring retainer 111 urges the enlarged heads 109′ into firm contactwith the cone 93 of the syringe, even if the flexible fingers 108′ areno longer capable of doing so. This position is illustrated in FIGS. 19and 20 .

As illustrated in FIG. 21 , the gripping means (109 or 109′) couldalternatively be provided in the form of a clip 112, inserted axiallyinto a slot 113 in the syringe holder so as to clip onto the front ofthe barrel.

Other means of providing a reaction surface for the front of the barrelso as to provide a compressive force during injection can be envisaged,for example a tapered elastomeric bush which could be snapped into placeonce the needle cover has passed during assembly. It may be possible togrip the frontmost part of the cone, where the needle enters the cone,rather than gripping the exterior thereof. Alternatively, other meansfor gripping the front shoulder of the barrel, or the exterior of thecone may be envisaged.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive.

Each feature disclosed in this specification (including any accompanyingclaims, abstract and drawings), may be replaced by alternative featuresserving the same, equivalent or similar purpose, unless expressly statedotherwise. Thus, unless expressly stated otherwise, each featuredisclosed is one example only of a generic series of equivalent orsimilar features.

The invention is not restricted to the details of any foregoingembodiments. The invention extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

1-27. (canceled)
 28. A syringe holder comprising: an elongated rearportion having an open end and a front portion comprising a plurality ofaxially extending flexible fingers; a cut-out in the elongated rearportion defining a viewing window configured to allow medicamentcontained in a syringe positioned inside the syringe holder to bevisible; radially spaced slots located adjacent the flexible fingers,where the flexible fingers each have an inward projecting grip such thatthe grip, in a normal position, forms a reaction surface for a frontshoulder the syringe; a radial flange that extends from an outsidesurface of the elongated rear portion; and an alignment tag projectingradially from the syringe holder; wherein the plurality of flexiblefingers and the radially spaced slots define a circular bore configuredto accept a removable needle cover positioned on the syringe and abutthe flexible fingers, wherein the syringe holder is configured such thatwhen the syringe is inserted axially into the open end and is slidablymoved axially towards the front portion, the grip flexes radiallyoutward from the normal position as the needle cover passes and thensprings back to the normal position, wherein the reaction surfaceprovides an axial compressive force on the barrel when a forward axialforce is applied to the syringe, and wherein when the grip is in thenormal position the flexible fingers fit within the circular bore thathas a diameter that prevents the flexible fingers from expandingradially outward from the normal position.
 29. The syringe holder ofclaim 28 where the syringe support comprises at least three flexiblefingers.
 30. The syringe holder according to claim 28, wherein each gripcomprises an inwardly directed surface.
 31. The syringe holder accordingto claim 28, wherein the syringe holder comprises two viewing windows.32. The syringe holder according to claim 31, wherein the alignment tagis configured to engage a longitudinal slot on inside surface of anouter housing when the syringe holder and outer housing are assembledtogether.
 33. An autoinjector comprising: a housing comprising a frontsection having a circular bore; a syringe support positioned within thehousing; a syringe comprising a barrel having a front shoulder, wherethe syringe is positioned within the syringe support and comprises aflexible finger having an inward projecting grip located on the flexiblefinger such that the grip, in a normal position, forms a reactionsurface for the front shoulder, where the syringe support furthercomprises a radial flange that extends from an outside surface of thesyringe support; wherein the front section has a circular boreconfigured to accept a removable needle cover positioned on the syringeand abut the flexible finger of the syringe support, wherein the syringesupport is configured such that when the syringe is inserted axiallyinto an open rear end of the syringe support, the grip flexes radiallyoutward from the normal position as the needle cover passes and thensprings back to the normal position, wherein the reaction surfaceprovides an axial compressive force on the barrel when a forward axialforce is applied to a plunger slidably positioned within the housing,and wherein when the grip is in the normal position the flexible fingerfits within the circular bore that has a diameter that prevents theflexible finger from expanding radially outward from the normalposition.
 34. The autoinjector of claim 33 where the syringe supportcomprises a plurality of flexible fingers.
 35. The autoinjectoraccording to claim 33, wherein the grip comprises an inwardly directedsurface.
 36. The autoinjector according to claim 33, wherein the syringesupport comprises a window.
 37. The autoinjector according to claim 33,wherein the outside surface of the syringe support further comprises analignment tag.
 38. The autoinjector according to claim 37, wherein thealignment tag project radially outward from the outside surface of thesyringe support.
 39. The autoinjector according to claim 37, wherein thefront housing has a bore therethrough, where an interior surface of thebore comprises a longitudinal slot positioned that accepts the alignmenttag when the syringe support and housing are assembled together.
 40. Theautoinjector according to claim 33, wherein the syringe support iscylindrical and has an inner diameter that is less than a diameter of afinger flange of the barrel so that the syringe support closelysurrounds the barrel of the syringe.
 41. The autoinjector according toclaim 33, wherein the rear end of the syringe support has a greaterouter diameter than a front end of the syringe support.
 42. A method ofassembling an autoinjector comprising the steps of: providing a syringecomprising a barrel, a needle at one end of the barrel, a plungerslidably position within the barrel, and a removeable needle cover forcontaining a needle sheath; providing a first part of an outer housinghaving a circular bore; providing a second part of the outer housing;providing a syringe support for supporting the barrel within the outerhousing, wherein the syringe support comprises a flexible finger havingan inward projecting grip located on an inner surface of the flexiblefinger such that the grip forms a reaction surface for a front shoulderof the barrel, where the syringe support further comprises a flange thatextends radially outward from an outside surface of the syringe support;axially inserting the syringe into an open rear end of the syringesupport until said syringe support supports the syringe, wherein thegrip flexes radially outward from a normal position as the needle coverpasses and then springs back to the normal position; axially sliding thesyringe and the syringe support relative to the first part of the outerhousing such that the grip is positioned within the circular bore andthe flexible fingers are prevented from flexing radially outward fromthe normal position due to abutment between the grip and an innersurface of the first part of the outer housing; and assembling the firstpart of the outer housing with the second part of the outer housing sothat the syringe support supports the syringe at an axial locationrelative to the outer housing, whereby in use the reaction surfaceprovides an axial compressive force on the barrel when a forward axialforce is applied to the plunger.
 43. A method according to claim 42,wherein the grip comprises and inwardly directed protrusions.
 44. Amethod according to claim 42, wherein said syringe support furthercomprises one or more alignment tags.
 45. A method according to claim44, wherein the one or more alignment tags are provided at a frontportion of the syringe support.
 46. A method according to claim 45,wherein the central bore has an interior surface with one or morelongitudinal slots, wherein the step of inserting the syringe and thesyringe support into first part of the outer housing comprisesassembling the front housing and syringe support together so that theone or more alignment tags locate in the one or more longitudinal slots.47. A method according to claim 42, wherein said syringe support iscylindrical and has an inner diameter less than a diameter of a fingerflange of the barrel so that the syringe support is suitably sized toclosely surround the barrel of the syringe.